Antioch police were sending out a warning Thursday aimed at the culprit behind numerous "rogue" radio broadcasts earlier this month on an emergency channel meant only for official use.
While listening to police and fire radio traffic is a common practice for newsrooms and even hobbyists, those listening to emergency transmissions can't talk back.
Yet Antioch police told KTVU that's exactly what someone did. They believe the transmissions were malicious and it could have serious consequences.
The recording KTVU obtained only lasts a second or two. One radio technician KTVU spoke with heard the brief broadcast live over Labor Day weekend.
The technician didn't want to be identified, but confirmed the broadcast went out on the frequency reserved for Antioch police.
"You hear like, bar noise in the background. And then I was hearing this "C'mon back, c'mon back,'" said the technician.
Police dispatch responded by broadcasting the following serious warning: "Be advised all channels of communication are being recorded and all violations noted are being sent to the FCC for referral to the Department of Justice for possible criminal prosecution before criminal court. Your immediate cessation of unauthorized radio traffic is required."
The anonymous radio technician was shocked someone would break the rules.
"This is not something you mess with," the technician said. "That's public safety and that's officer safety."
Police said rogue transmissions can get in the way of officers trying to communicate during an emergency.
"It's actually very dangerous, not only for the officers, but to the public as well," said Antioch Police Lt. Tammany Brooks. "Officers are unable to talk on police radio, dispatchers are unable to provide emergency communications to the officers to have them respond to help the public."
Police said the unauthorized broadcasts stopped after they read that FCC warning.
The department hopes to soon move to an upgraded radio system with encrypted channels, but it's expected to cost Antioch police about a million dollars.
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